1. Technical Field
This invention relates to the field of reticles. More specifically, the invention relates to reticle capturing and handling.
2. Background Art
Reticles or masks are employed in lithographic systems for fabricating circuits in semiconductor wafers or other substrates. Typically, a pellicle that is parallel to the reticle is secured to the reticle by a pellicle frame near the edge of the reticle. The combined pellicle and reticle apparatus or the reticle alone must be moved within the clean room environment. Accordingly, the reticle must be captured and moved manually or by an automated handling system.
Prior manual and automated handling systems have required contact with the bottom and/or top surface of the reticle, have interfered with the pellicle or pellicle frame, or have been unreliable and susceptible to dropping the reticle. Some handling systems have only been useful for a particular size of reticle, and some have not provided sufficient cleanliness for a clean room environment.
The present invention provides a novel reticle design, a novel reticle capturing system, and a novel method of capturing a reticle that overcome the problems described above. According to the present invention, a reticle includes a substrate defining a recess that extends into the substrate from an edge thereof. In one embodiment, the substrate defines a first recess and an opposing second recess, and the substrate may define more than two such recesses.
The invention also includes a reticle capturing system that includes a reticle. In an embodiment, the reticle defines a first recess extending into the reticle from a first edge of the reticle and a second recess extending into the reticle from a second edge of the reticle. The reticle capturing system also includes a first finger selectively extending into the first recess and a second finger selectively extending into the second recess. The first and second fingers may be tapered so that the reticle capturing system will be self centering. The reticle capturing system may also include a third recess defined by the reticle and a third finger selectively extending into a recess.
The invention also includes a method for capturing a reticle that includes providing a reticle that defines a recess extending into the reticle from an edge thereof, and inserting the finger into the recess. The method may further include inserting a second finger into a second recess.
The present invention provides many advantages. First, there is no need to touch the top surface or the bottom main surface of the reticle so there is virtually no risk of damaging the pattern formed on the reticle, and the reticle capturing system may be used for virtually any type or shape of pellicle or pellicle frame. Second, the mating of recesses with fingers holds the reticle securely with little risk of it being dropped, even for heavy reticles such as 9 inch reticles. Third, because the recesses extend inwardly from the periphery of the reticle, the area of the reticle that is transparent and can be effectively used is not diminished. Fourth, the tapered recesses and tapered fingers are self-centering so that the fingers need only be substantially aligned before being inserted into corresponding tapered recesses; once the fingers are fully extended into the recesses, the reticle is precisely positioned within the reticle capturing system. The present invention is particularly useful for automated handling of reticles, but it also provides beneficial results if it is used as a manual reticle handler.
The foregoing and other features and advantages of the present invention will be apparent from the following more particular description of preferred embodiments of the invention, as illustrated in the accompanying drawings.